Canberra PV Solar Hot Water

What Is PV Solar Hot Water

PV, or Photovoltaic, is energy that is created by the sun and converted into electricity via panels on your roof, most commonly seen on your standard home solar grid connections.

PV Solar Hot Water uses the DC electricity created by the panels and directly uses it to heat your hot water. 

Advantages of PV Solar Hot Water in Canberra over the old style Solar Hot Water systems in Canberra

Ok, so for this question we need to get slightly technical and so I will start with how a standard water or glycol solar panel hot water system works. 

With an old fashioned solar hot water heater, collectors, aka panels or evacuated tubes, are placed on the roof and your water from your hot water tank is circulated through the collectors by means of a small circulating pump controlled by a roof sensor and tank sensor, the fluid is heated by the sun and then returns to the tank.

Disadvantages of old style Solar Hot Water Heaters

These systems have three major floors in them

  1. On hot days, when the water has reached temperature, due to the water in the panels being under constant pressure, the water is actually superheated and as the water is under pressure, the temperature if left without a control measure would exceed 100 degrees. The control measure for water based systems is to start dumping hot water so that it is replaced with cold water on the incoming side, therefore cooling down the overall temperature of the stored water. In climates such as Canberra, where during summer we have long hot days, this can amount to a huge waste of water, which is one of the earth’s most precious resources. 

  2. On Freezing Cold Day’s, water wants to Freeze, which is a disaster in a plumbing system and will cause major damage to the collectors and other infrastructure if it does do so. To prevent this, most solar systems use one of two anti frost devices.

    1. The first is a mechanical anti frost valve installed on the panels on the roof. These valves automatically open when the temperature drops to about 4 degrees which dumps water on the roof, therefore allowing hot water from the tank to replace it and keep the panels warm. Not only does this method waste water, however, it also wastes hot water. During times of low solar, you have likely paid for electricity to heat that water via your booster, therefore wasting both water and electricity. 

    2. The second type of anti frost system commonly used in old style solar hot water systems, relies on the top sensor to detect when the temperature has dropped. When the temperature has dropped below approximately 4 degrees, the circulating pump turns on and it heats the panel with the hot water stored in the tank. Again, if you’re using your electrical booster to heat that water, you are paying for electricity to heat your solar panels and for electricity to run the pump. Another issue with these control measures is they rely on a small solar controller computer and small sensors. If/When one of them fails, the anti frost won’t kick in and you could be left with thousands of dollars damage when your panels split. 

  3. The third major floor in them is the amount of points of failure and the difficulty in knowing whether or not your system is working correctly. All of the following parts in a  mechanical old style hot water system can, and will, fail eventually. The circulating pump, top sensor, bottom sensor, solar computer, anti frost valves, flow valve, air relief valve, panels and so on. These are all mechanical devices, other than the computer, and in time will need replacing. What’s more, when these parts fail, you are often none the wiser and without knowing it you could be operating for years receiving no solar benefit and heating your water from your booster. The ongoing maintenance on an old style solar hot water system is considerable and generally makes the economics of installing one not viable. 

Note – Different models have slightly different methods of operation. Some, like Glycol systems, may not be susceptible to all of the above, however, do come with other complications such as heat exchangers and significant additional purchase costs. All of them have weaknesses and issues so I won’t go into each and every system.

Given Canberra’s hot water climate, with extremely hot days in summer and extremely cold days in winter, these old type of hot water systems are just not suitable. 

Advantages of PV Solar Hot Water Systems Over Old Style Solar Hot Water Systems in Canberra

Other than the standard components of a storage electric hot water system, A Modern PV Solar Hot Water System has only the electricity producing panels, and a DC chopper (a device which cleans the electricity to make it smooth and useable in the hot water system). Both of these parts are extremely reliable, have no moving parts and require little to no maintenance. They are not susceptible to frost, have no mechanical parts that are likely to break, and excess sun/energy does not super heat the water.

Whereas the old water or glycol panel style of Solar hot water system requires the flow and return water lines to the panel to have fall back to the tank, often limiting where the location of the tank can be installed. A PV solar hot water system only needs a wire to travel between the tank and the solar panels, so you can place your tank anywhere you like, preferably much closer to your plumbing fixtures.

A PV solar hot water system is completely independent of all other energy systems and does not need to be connected to the main’s power electricity in order for it to operate. The only exception to this is if you use a booster, which would operate independently and only be required in high demand situations or after long periods of low solar activity.  

Why PV Solar Hot Water System Over or In Addition to a PV Grid Connected Electrical System

In most home’s, your hot water consumption accounts for approximately 70% of your total energy consumption in summer and up to 50% of your total energy consumption during winter. 

PV Grid connected systems, that create DC electricity using PV panels, convert the DC electricity into AC electricity, which is what we use in our homes, through an inverter. Once converted, this electricity can be used by your home Only at that point if you’re currently using an electrical appliance. If you’re not using electricity at that exact point in time then the power is pushed through the electrical grid. You receive a very small rebate for the electricity you have produced and your electricity goes on to supply a neighbour who is using power at that point in time. When you sell electricity into the grid, you are selling it at a fraction of the cost that you buy it for. At the time of writing this, in the ACT the current rebate price is around 9 cents per KWH and the price you pay when you buy it back is around 25 cents per KWH. This means you need to create 2.7 KWH X the amount of power you actually need if you want to make your bill disappear. 

When you connect an independent PV solar grid to a hot water system, you are effectively creating the most environmentally friendly, efficient and cheapest battery known to mankind. In essence, what you are doing is taking the green energy created by the sun, and storing the energy in water to use at a time that is convenient for you, just like a battery. Whereas a standard battery use’s acids and chemicals to store the energy, a hot water system use’s only H20 (water), which you will be using regardless of the energy method used to heat it. The environmental impact of current day batteries is questionable to the overall environmental benefit of having them installed. 

NOTE – We are all for people investing in battery technology as this investment overtime will see huge improvements in the field, making them more efficient and more environmentally friendly. It is simply our opinion that your first energy storage system should be your hot water system, as this is the most beneficial to the environment and your wallet.    

If you already have or plan on getting the maximum sized home Solar PV grid connected system, 6.6KW, installing a direct fed PV Solar Hot Water System increases your solar creating capacity. 

Google Reviews

  • Gillian Sloan

    From my first conversation with Tom, I was treated in a very professional manner. The quote I was given was fair. Nathan and Aaron were two polite young men who dealt with my plumbing problem promptly and expertly, leaving my house so clean. Excellent workmanship and customer care. I highly recommend Water Tight Canberra. Thank you!!

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  • Geoff Young

    We have been chasing a plumber for months in Canberra, when today we saw Water tight in their van at a neighbor. One call and the wonderful receptionist organised for Aaron to come over in his Lunch and fix our major shower blockage. What can I say, OMG!!! This is service, Aaron would not settle for anything less than perfection. Pulled the shower apart, explained in detail to me everything that was happening and found the annoying problem. A old piece of plastic off the washer stuck in the pipe. He even gave me great advice on our toilet issues and over pressure issues. Unbelievable service, more intent on fixing the problem and doing it right than ripping us off. I wholeheartedly recommend Water Tight Canberra and especially Aaron as the no 1 plumbing service in Australia.

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  • darko reljic

    Hooked up my new sink and works great

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  • Allan Baxter

    I arrived at my townhouse on a Friday afternoon at about 1:30 after a week away to find that the hot water service had sprung a leak during my absence. I called Water Tight and a representative (Tom) was here within an hour. After an inspection and quotation Tom undertook to replace the HWS that day and did so with two other members of staff. I was very favourably impressed with the prompt and efficient service. I would recommend Water Tight to anyone with an urgent plumbing problem.

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  • vylan07

    Water Tight provided an excellent job on 25/02/2019. They located the burst water pipe and repaired it immediately. We are so happy with the great service and the professional crew. I strongly recommend this company for any plumbing need that you have.

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